Usually, water or powder form of fire extinguishing agents has been employed to quench ordinary fires. Water, however, which has high freezing point, 0° C., is difficult to use in cold places or outdoors in the winter season. The powder form of fire-extinguishing agents may cause significant secondary damages after the extinction of flames, and they should be rocked or swung at least once every six months lest they will solidify during storage. In addition, the powder agents are difficult to store in humid places. For controlling forest fires, which is an A class fire, foam phase fire extinguishing agents are being used, but they do not show desired performance. For these situations, there has been extensive research to develop new powerful neuter loaded stream fire extinguishing agents. On the whole, the extinguishing power of loaded stream fire extinguishing agents are known to efficient in controlling oil fires, a B class fire; however, they are insufficient for controlling an A class fire, such as a forest fire. For these reasons, development of a neuter loaded stream fire extinguishing agents, which have not only an excellent efficiency in fire control but also environmentally friendly, is in high demand.
Some advanced country, like U.S or Japan, has come into, marketing neuter loaded stream extinguishants for controlling B class fires, which are nontoxic nor harmless to the human body and cause no corrosion to various metal, became they have legal stipulations requiring the use of a neuter loaded stream extinguishers only. However, neuter loaded stream extinguisher with highly effective in controlling A class fires, non corrosive to metal, and friendly to environments have not developed.
Alkaline aqueous solution of loaded stream extinguishers may cause secondary problems: harmful to human body and corrosive to particular parts of automatic fire extinguishers. Although they have a strong extinguishing power, the loaded stream extinguishants with high alkalinity cannot be put on the market. While demand for neuter loaded stream extinguishers will drastically increase all over the world, legal regulations for corrosion prevention and safety for human body will be reinforced and stringent.
Fire extinguishers are introduced in many patents. For example, U.S. Pat. No. 5,909,776 discloses a fire extinguisher containing a gel-type, fire-extinguishing composition comprising a gas selected from the group consisting of a perfluorocarbon, a hydrochlorofluorocarbon, and a hydrofluorocarbon, into which particles of dry powder fire-extinguishing agent having average particle sizes of 500 microns are dispersed, along with a surfactant and a deflocculant stabilizer.
U.S. Pat. No. 5,651,416 describes a fire extinguishing method, which uses an extinguisher comprising an alkaline metal salt or an ammonium salt of acetate, chloride or bromide, a freezing point suppressant, a surfactant, and water.
Korean Pat. Registration Publication No. 93-3391 discloses a fire extinguishing composition comprising a C1–C5 halogenoalkane selected from the group consisting of bromochlorodifluoromethane, bromotrifluoromethane, dibromofluoromethane and mixtures thereof, and an organic phosphorous compound selected from the group consisting of trialkylphosphate, triarylphosphate, and trihalogenoalkylphosphate.
Korean Pat. Registration Publication No. 97-9308 disclosed a fire extinguishing composition comprising an extract from a plant selected from among sapindaceae, cruciferae, leguminosae, ulnaceae, and combinations thereof, and a surfactant such as dodecyl polyetheneoxy sodium sulfate or sodium dodecyl aminopropionate.
Methods of preparing liquid extinguishants are also disclosed in Korean Pat. No. 117936. Urea, trisodium phosphate, ammonium bicarbonate and sodium carbonate are dissolved, in order, in aqueous solution of ammonium sulfate to produce a liquid extinguishant. A method suggested by Korean Pat. No. 259512 comprises dissolving trisodium phosphate, ammonium sulfate, and urea, in order, in aqueous solution of soda ash. In Korean Pat. No. 112862, an extinguisher is prepared from a mixture of an aqueous solution of ammonium bicarbonate and sodium phosphate, an aqueous solution of urea, ammonium sulfate, and sodium carbonate, and an aqueous solution containing calcium chloride in liquid aluminum sulfate.
The conventional fire extinguishing agents as above mentioned have poor extinguishing power to control A class fires, such as forest fires, and have insufficient flame retardant. Further, the said fire extinguishing agents cause secondary damages: toxicity to human bodies, contamination of soil, and corrosion of extinguisher parts, which are attributable to the alkalinity thereof.
Thus, there remains a need for an improved neuter extinguishing system that has an excellent in extinguishing power to quench A class fires, as well as environmentally friendly.